These are both decent guides:

• https://www.privacyguides.org/en/os/ios-overview/
• https://github.com/iPrivacyGuides/iOS-Privacy-Guide

For your ad blocking question, AdGuard is my recommendation.

I use AdGuard to great effect on my iOS devices.

The Complete iOS Privacy & Security Guide from Techlore

i don’t use nextDNS but if i had the limitations of ios on my main machine, i probably would end up using it ☞ https://nextdns.io/

Apple’s limitations are frustrating

I use Adblock plus, Ghostery and 1Blocker for fingerprinting as Safari extensions for iOS and Mac. They do an alright job for fingerprinting and do well with ads. Just make sure to go into Adblock plus and disable “allowable ads” so that none break through.

I’d say the better iOS browser is Snow Haze. Unfortunately iOS blocks a lot of the privacy stuff to conform with its guidelines so the locked down Firefox derivatives aren’t as strong as on android. Snow haze is the only privacy browser I know that works within the iOS confines and maximizes it. They also have an extension for Firefox if you want to go that route.

I stopped using chromium based browsers, so others may have recs on those.

Wipr 2 is a great paid ad blocker. Unfortunately most iOS blockers don’t work too well beyond this one and AdGuard (and I haven’t had the greatest experience with the latter either)

Good luck with privacy there. At minimum disable the AI stuff that has access to every app, and that’s if you believe their toggles do anything, which Apple has been proven to not listen to them in the past